Safety device to restrict operation of switch control levers



Aug. 12, 1958 H. J. PEARCE 2,847,526

SAFETY DEVICE TO RESTRICT OPERATION OF SWITCH CONTROL LEVERS Filed June 21, 1957 FIG.|.

INVENTOR.

H.J.PEARCE g 4 HIS ATTORNEY SAFETY DEVICE TO RESTRICT OPERATION OF SWITCH CONTROL LEVERS Heyward J. Pearce, Rochester, N. Y., assignor to General This invention relates to control and indication devices for railway traffic controlling systems, and more particularly to a safety device to prevent the operation of a control lever of such a device when such control lever and the apparatus controlled thereby is out of service.

In railway traffic controlling systems the remote track switches are normally controlled by an operator from a central location by means of switch control levers located on a master panel, as for example, such as is shown and described in U. S. Pat. No. 2,720,640, dated October 11, 1955. There are times, however, due'to track repairs, switch machine maintenance, changing out relays, or for various other reasons, when it is desirable to cut such track sections and associated devices out of service so far as their remote control is concerned.

During such out of service periods, the operator is informed and under ordinary circumstances the affected switch control levers are not operated. However, due to oversight or a change of operators, it is possible that such a switch control lever may be inadvertently operated and when current is restored, the remote track switch apparatus would function, possibly causing injury to the maintainer or some other damage.

The present invention contemplates the use of a safety knob which, when placed over the knob structure of the switch control lever, prevents the normal turning of the switch control lever. In general, the safety knob comprises a molded plastic form of substantial cylindrical shape, preferably red in color to attract attention. Thus, when the safety knob is in place over the switch control lever, its color alone indicates that the switch control lever so marked is out of service and should not be operated.

Provision is also made so that in case the warning color is disregarded, any attempt to rotate the safety knob would merely result in free rotation of the safety knob about the knob structure of the switch control lever. Also, the present invention contemplates placing a cap with a small opening therein over the outer end of the cylindrical safety knob mainly for the purpose of assuring that the safety knob can be placed over the switch control lever in one way only. The small opening in the cap makes it possible to still see the arrow indicators, numbers or such as maybe on the front of the switch control levers.

Other objects, purposes and characteristic features of the present invention, which is shown in two forms, will appear as the description progresses and reference will be made to the accompanying drawings in which like parts are designated by like reference characters and in which:

'.Fig. l is a front view of a typical railway traffic controlling system control panel layout having two switch control levers thereon, one of which is covered by a safety knob device comprising one form of the present invention;

Fig. 2 is a perspective view of a switch control lever mounted on a panel as shown in Fig. 1;

Patented Aug. 12, 1958 Fig. 2Ais an exploded perspective view showing the elements comprising the safety knob device of the form of the invention shown in Fig. 1, and shown on the same plane as Fig. 2 to illustrate their positions in relation to each other when the safety knob is being applied to the switch control lever;

Fig. 3 is a back end view of the safety knob device of the formof the invention shown in Fig. 1;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1 and shows the safety knob elements in section with the switch control lever and panel indicated by dot and dash lines;

Fig. 5 is a perspective view of another switch control lever mounted on a panel and similar to Fig. 2;

Fig. 5A is a perspective view of the other more simplified form of safety knob of the present invention and is shown on the same plane as Fig. 5 to illustrate their positions in relation to each other when the safety knob is being applied to the switch control lever;

Fig. 6 is a back end view of the safety knob device of the form of the invention shown in Fig. 5A; and

Fig. 7 is a sectional view taken on the line 7-7 of Fig. 6 showing the safety knob form shown in Fig. 5A.

Referring now more particularly to the first form of the invention 'shown in Figs. l-4 inclusive, the safety knob SK has been shown applied to one of the switch control levers L of a typical control panel for railway control systems, assuming that such switch control lever L is out of service for some particular reason. For the purpose of illustration, there has been chosen switch control levers as shown in the above mentioned U. S. Pat. No. 2,720,640, although it should be obvious that the invention could be applied to other types of control switches and buttons.

Briefly, the panel 11 is inscribed to illustrate a main railroad track 12 with two switch turnouts 13 and 14 converging therefrom, thus simulating the actual track section to be controlled thereby. Each of the track switch turnouts 13 and 14 is provided with a switch control lever L to control the movements of its corresponding remote track switch. The rotary operation of the control knob 15 of. a switch control lever L conditions control circuits for its associated track switch and also positions an associated switch point indicator 16 which indicates the position of the track switch on the panel 11.

The control knob 15, when mounted, is spaced away from the panel 11 by the hub 17 of the switch point indicator 16, and is provided with a fin 18 on each side to provide a grip to facilitate rotation. This control knob 15 is also hollow and has a glass insert 19 in its front end behind which is a lamp. An indication marker, such as a direction arrow 20, appears on the glass insert 19, and may be lit up by the lamp under certain operating conditions.

The safety knob SK comprises a molded plastic cylindrical form 25 which is preferably red in color, a split slip ring 26 and a front cover cap 27. The cylindrical knob 25 is provided with a groove 28 in its inside surface to accommodate the slip ring 26 and a groove 29 in its outside surface to facilitate the attachment of the cover cap 27. v

The slip ring 26 has a notch 30 in one side of its inner surface and directly opposite on its other side it is split and terminates into two ends 31, thus forming an opening 32 the same length as the notch 30. The slip ring 26 is assembled in the cylindrical knob 25 by compressing the two ends 31 together, thereby reducing its diameter by closing the gap in the opening 32, thus permitting the slip ring 26 to be inserted into the cylindrical knob 25, whereupon it engages the groove 28; Once the slip ring 26 is in the gtbsfllfi, it will expand and thus be held in place. The cooperation between the slip ring 26 and the groove 28 is such that the slip ring normally is held by friction and will rotate with the cylindrical knob 25, but if for any reason the slip ring 26 is held, the cylindrical knob 25 may be rotated about the slip ring 26.

The cover cap 27 is provided with prongs 33 so that, when placed over the outer end of the cylindrical knob 25, the prongs 33 may be bent into the groove 29, thus holding the cover cap 27 in place. slightly larger than the glass insert 19 is provided in the front of the cover cap 27 so that the front of the control lever knob is visible when the safety knob SK is in place on the control lever L. This cover cap 27 also serves as a means to insure placing the safety knob SK over the control knob 15 properly with the slip ring end first and also makes it impossible to maliciously rotate the control knob 15 by deliberately using an appropriate tool to reach through the front opening of the safety knob SK and grasp the fins 18 of the control knob 15. Further, the safety cap 27 may be made of suitable sheet metal or may be provided with a white pad to permit the operator to make notations in pencil thereon, such as the time such control lever was rendered out of service or the like.

As previously mentioned, let us assume that the operator at the control tower has been informed to cut the control lever L at the switch turnout 13 out of service because of maintenance work or such taking place at the remote location of the switch operating apparatus. He then places a safety knob device SK, which is red in color, over the control lever knob 15 to serve as a warning not to operate said control lever L. When placing the safety knob device SK over the control lever knob 15, the notch 36 and the opening 32 in the slip ring 26 slide over the fins 18 on the knob 15. With the safety knob SK fully in place, the slip ring 26 will be beyond the fins 18 and a slight rotation of the safety knob will move the notch 30 and opening 32 out of alignment with the fins 18 and place the slip ring 26 behind the shoulders of the fins 18, thus preventing the safety knob SK from being pulled off or accidentally falling off. The glass insert 19 and its indication arrow 20 will still be visible to the operator through the opening 34 in the cover cap 27.

Supposing now that the warning signified by the red color of the safety knob SK is ignored for some reason or inadvertently an attempt is made to operate the switch control lever L which is out of service, any rotation of the safety knob SK will merely cause it to rotate harmlessly about the control lever knob 15 with the slip ring 26 turning on the hub 17-of the switch point indicator 16. Also, if for some reason the safety knob SK was not fully in place over the control lever knob 15 and the notch 3% and opening 32 of the slip ring 26 were still in contact with the fins 18 of the knob 15, it can be seen that the slip ring 26 would be held against rotation. Thus, an attempt to rotate the safety knob SK would overcome the friction and cause slippage between the groove 28 and the slip ring 26 as the amount of friction is not sutficient to equal the force required to rotate the control lever knob 15. Consequently, only the cylindrical knob would rotate.

When the operator is informed that service has been restored and the affected control lever L is again ready for service, he merely rotates the safety knob SK until the notch 30 and the opening 32 in the slip ring 26 are in alignment with the fins 18 on the control lever knob 15, whereupon the safety knob SK may be removed.

Referring now to Figs. 5, 5A, 6 and 7 which illustrate a more simplified form which the invention may assume, the safety knob SKI comprises a molded plastic cylindrical form which is provided with a shoulder portion 41 located on the inside at its inner end. Two notches 42 are located opposite to each other and so An opening 34 l spaced and sized to cooperate with the fins 18 on the control lever knob 15 in a manner much the same as the slip ring 26 already shown and described. Here again, the safety knob SK1 may be slipped over the control lever knob 15 when the notches 42 and the fins 18 are in alignment, whereupon a slight rotation of the safety knob SKI will position the shoulder portion 41 behind the shoulders on the fins 18. The safety knob 8K1 can then be rotated freely about the control lever knob 15 with the shoulder portion 41 turning on the hub 17 of the switch point indicator 16. Also, it should be understood that the outer end of the cylindrical knob 40 could be provided with a groove and a cover cap similar to the groove 29 and the cover cap 27 as shown applied to the cylindrical knob 25 in the first form of the invention.

Having shown and described two forms of the invention as applied to a conventional switch control lever, it is desired to be understood that the invention could assume other forms of structure and detail and could be applied to other forms of switch control levers, all without departing from the spirit or scope of the present invention as defined in the appending claims.

What I claim is:

1. A safety device to restrict the operation of a switch control lever comprising a hollow cylindrical knob of a distinctive warning color and having means formed on its inside surface to permit attachment to said switch control lever yet prevent operation of said switch control lever when said cylindrical knob is rotated.

2. In a safety device for preventing the operation of a switch control lever which is out of service, a hollow cylindrical knob of a distinctive warning color, means formed on the inside surface of said cylindrical knob to facilitate attachment thereof to said switch control lever, said means of attachment permitting free movement of said cylindrical knob about said switch control lever when said cylindrical knob is rotated.

3. In a safety device for preventing the operation of a switch control lever which is out of service, a hollow cylindrical knob of a distinctive warning color, a shouldered bushing formed on the inside surface near one end of said cylindrical knob and having two notches therein disposed opposite to each other, a cover cap with an opening therein attached to the other end of said cylindrical knob to insure proper mounting and visibility of said switch control lever, said bushing and said notches cooperating with said switch control lever when said cylindrical knob is attached thereto in a manner whereby said cylindrical knob when rotated will move freely about said switch control lever.

4. In a safety device for preventing the operation of a switch control lever which is out of service, a hollow cylindrical knob of a distinctive warning color, an open end biased slip ring frictionally fitted into a groove located on the inside surface near one end of said cylindrical knob, and having a notch therein disposed opposite to its open end, a cover cap with an opening there in attached to the other end of said cylindrical knob to insure proper mounting and visibility of said switch control lever, said notch and said open end of said slip ring cooperating with fins and shoulders on said switch control lever when said cylindrical knob is attached thereto in a manner whereby said cylindrical knob when rotated will move freely about said switch control lever, and whereby said frictionally mounted slip ring will permit free movement of said cylindrical knob even though said slip ring may be improperly held by said fins on said switch control lever.

References (Jited in the file of this patent UNITED STATES PATENTS 2,667,864 Marx Feb. 2, 1954 

